1. Field of the Invention
The present invention relates to an air conditioner in which the power (capacity) of a compressor is controllable (variable) in accordance with an air conditioning load.
2. Description of the Related Art
There is generally known an air conditioner (separation type air conditioner)in which plural indoor units are linked to plural outdoor units, and a compressor, a condenser, an expansion device and an evaporator are successively linked to one another to construct a refrigerant circuit. In this type air conditioner, the power (capacity) of the compressor as described above is controlled to be varied in accordance with an air conditioning load. In order to vary the power of the compressor, there has been hitherto proposed an inverter type compressor which controls its power by varying the frequency of power to be supplied to the compressor.
However, when an inverter compressor is used in the air conditioner as described above, the price of the air conditioner rises up unavoidably. In addition, the frequency components may have various adverse effects on peripheral electrical elements such as a microcomputer, etc. which are disposed around the inverter compressor. For example, the peripheral electrical elements suffer noises or a condenser (electrical part) is broken down.
On the other hand, there may be considered another type air conditioner which does not use any inverter compressor, and uses a rated compressor (a compressor whose power is invariable) and a refrigerant return mechanism for returning a part of refrigerant discharged from the rated compressor to a suck-in side of the compressor (for example, an accumulator) to perform multistage control operation with the rated compressor. However, this type air conditioner has such a disadvantage that the control operation cannot be smoothly performed, resulting in occurrence of hunting and limitation of the control range to an extremely narrow range. The occurrence of the hunting intensifies the fluctuation of a room temperature, so that a comfortable air conditioning atmosphere is unachievable.
Such a phenomenon becomes a critical problem particularly to a so-called large-capacity type air conditioner having plural outdoor units.
Further, when increase in power (horsepower) which is demanded in design (hereinafter referred to as "demand horsepower on design") is needed in the air conditioner as described above, it has been a general way to increase the number of outdoor units and link these plural outdoor units to one another to fabricate a so-called multi-type air conditioner.
When the demand horsepower on design is increased to fabricate an air conditioner having a high efficiency, in some cases it is better to increase the horsepower of an outdoor unit itself rather than to increase the number of outdoor units. However, there has not been hitherto proposed any outdoor unit which is usable in a separation type air conditioner having a large horsepower. If the outdoor unit is designed to have a large capacity, the number of compressors must be increased, and the capacity of a heat exchanger, an accumulator, etc. must be also increased. However, there has not been hitherto proposed any technical idea for efficiently accommodating various elements (such as a compressor, a heat exchanger, an accumulator, etc.) constituting the refrigerant circuit into the main body of an outdoor unit, and effectively performing maintenance of these accommodated elements.